1. Field of the Invention
The present invention relates to a fingerprint matching apparatus, and more particularly to a fingerprint matching apparatus including a fingerprint distortion detection unit which detects that a correlation object (object person) intentionally distorts a fingerprint because the object wishes that the fingerprint correlation fails.
2. Description of the Related Art
Recently, immigration investigation of each country has been strict. Lately, there has been proposed an idea of strict immigration investigation which uses biometrics. This idea acquires images of the face and the fingerprint of an immigrant or a migrant and employs biometrics certification to judge whether or not the immigrant or the migrant is a person on a blacklist. Further, there has been proposed another technique that an IC chip, in which biometrics data such as face and fingerprint images are recorded along with identification of the immigrant or migrant, is embedded in a passport and strictly verifies the passport holder with reference to the data in the IC chip. Still further, since an electronic passport can be read by a machine, there is proposed a rapid self-service immigration investigation, in which immigration investigation is performed by an immigrant or a migrant operating a machine to read a passport in a booth with no stuff clerk and inputting the face and the fingerprint images. If such immigration investigation without a stuff clerk is accomplished, it is important to verify the passport holder and correlate the passport holder with a person on a blacklist.
Various techniques have been conventionally proposed to improve the accuracy in fingerprint correlation.
For example, if a correlation object presses the finger on a fingerprint reading face of a fingerprint matching apparatus too weakly or too strongly, an accurate fingerprint image cannot be acquired. As a solution, there is a technique in which a fingerprint is read at the time when a constant pressure is applied to the fingerprint reading face by the finger (Patent Reference 1).
Another technique discloses that a body part of a correlation object is forced to be held on a reading position, and biometrics data is read in the holding state, so that the biometrics data is finely read even if the correlation object does not get used to operation of the correlation matching unit (Patent Reference 2).
Conventionally, a fingerprint matching unit is used for identification verification, in which a correlation object carries out fingerprint correlation and, if the object is not verified for some reason, the object attempts another fingerprint correlation or takes alternative means for identification verification. Since a correlation object him/herself is harmed by failure in fingerprint correlation, such a conventional fingerprint matching unit asks the correlation object to re-put the finger on the fingerprint reading face of the fingerprint matching unit such that the fingerprint correlation succeeds.
On the other hand, if such a conventional fingerprint matching unit is used for finding a person on a blacklist, it is important to accurately judge whether or not a fingerprint image of a correlation object is identical to any fingerprint image previously retained in a blacklist. If a correlation object is really a person on a blacklist, success in fingerprint correlation, that is judgment to be a person on a blacklist, is not preferable for the object. Therefore, there is a possibility that the correlation object intentionally fails fingerprint correlation by distorting the fingerprint. However, a fingerprint matching unit has a limited capability of correlation, intentional distortion of the fingerprint by the correlation object results in an increase in the probability of fingerprint correlation failure. If fingerprint correlation fails, the correlation object is judged not to be a person on a blacklist. In this case, the fingerprint matching unit misses finding the correlation object to be a person on a blacklist.
[Patent Reference 1] Japanese Patent Application Laid-OPEN NO. HEI 11-225998
[Patent Reference 2] Japanese Patent Application Laid-OPEN NO. 2003-058870